This invention relates to a telecommunications device, and in particular to a method for compensating for changes in the temperature of the device, and to a device operating in accordance with the method.
Typically, telecommunications devices include an oscillator, which is used to generate signals at a known frequency, in order to be able to transmit and receive signals successfully at the required frequencies. It is known that such oscillators have temperature dependent frequency characteristics. Where the signals need to be generated such that their frequency is known with a very high degree of accuracy and stability, for example in Global Navigation Satellite System (GNSS) receivers, it is common to try to minimize, and then to compensate for, changes in the temperature of the oscillator.
U.S. Pat. No. 6,630,872 relates to a communications receiver, in which signal reception relies on a signal generated by an oscillator circuit in the receiver. It is known that such oscillator circuits are sensitive to changes in ambient temperature, and the document discloses a system in which a temperature sensor is coupled to the oscillator. A thermal model of the oscillator and its environment is used, so that a temperature value generated by the temperature sensor can be used to estimate a true temperature of the oscillator. Knowledge of the temperature-frequency characteristic of the oscillator can then be used to estimate the true frequency of the signal generated by the oscillator circuit.